In the manufacture of jeans style pants, the operations of attaching and finishing the left fly are very difficult sewing operations and ones that have a large influence on the appearance quality of the finished garment. The quality aspects is of particular importance on the finishing operation which involves sewing the outline of a "J" which is readily visible on the front of the garment. It is important that the curved part of the "J" be a uniform radius and that the stem of the "J" be parallel to the edge of the fly.
With the typical manual method of sewing using a sewing machine, the operator must guess at the radius of the curve and estimate where the edge of the fly is in order for the stem of the "J" to come out parallel. This is made all the more difficult in that while the operator is carrying out these operations, the garment is face down on the sewing machine bed such that the operator cannot see the appearance of the final product.
In all of the various sizes, types and styles of jeans, the only variable in the size of the fly is the length. The width of all flys are the same and the curved portion of the "J" is always a constant, as is the relation between the bottom of the fly assembly to the "J".
Although numerous sewing machines, supporting beds and clamping devices are known for assembling fly flap portions of a garment, and inserting and sewing a fly into the garment, no devices are known which are capable of consistently and accurately sewing the "J" stitch pattern to attach and finish the left fly to a jeans style garment.